Telephone system



C. W. KECKLER. TELEPHONE SYSTEM.

APPLICATION FI'LED OCT-2,1917.

Patented Apr. 6, 1920.

1 M w/won (haw/gs W Kerk/PK UNITED STATES PATENT oEEioE.

CHARLES W. KECKLER, OF'NEWARK, NEW 'JE sE AssIeNoE TO WEs'rEEN ELECTRIC- COMPANY, INCORPORATED, on NEW 03K, N. Y,, AcoEroEArIoN OF EW roan. 1

TELEPHONE sYs'rEM.

' Specification of Letters Patent.

Application filed October 2, 1917. Serial No. 194,304.

oflice and multipled to each of the stations.

included in the intercommunicating system.

The object of this invention is to provide improved holding means for the trunk circuit by means of which electrical continuity of the trunk circuit may be maintained while the original answering station of the system is communicating with another station thereof, thereby to prevent the actuation of the disconnect signal at the central ofiice end of the trunk circuit.

In accordance with this invention, there is provided a bridge which includes a relay winding for holding the trunk circuit in substitution of a telephone set and jmeans for substituting the locally energized relay gized is locked up under control of the bridged relay.

For a more complete this invention reference should be had to the following description consideredin connection withthe accompanying drawing containing one embodiment of the invention;

In the drawing there is shown 'a trunk circuit comprising conductors 5 and 6,,which extend to a central office, not shown. This trunk circuit is multipled to the various st a. tions comprising the system, only two of which, A and B, are shown in the drawing. Each station of the systemis provided with the usual telephone set,.a trunk answering key T for connecting the telephone set with the trunk circuit, a local answering for connecting the telephone set withconductors of the interconnecting system individual to the particular answering station, and with the usualkeys (1 and. 2 being shown at stations B and A respectively). which are individual to the other stations of the system and which are emploved for connecting the telephone set of a calling station ith th co duct s ndi idual to ny called 1, CHARLES WV. KEcKLER,

bridge comprising a which when ener-j understanding of contact, short'circuits the winding ey L.

Patented Apr. 6, 19 20.

station of the system. Each of these individual keys is provided with a third contact 12 engaged when the key is depressed to its way-down position for closing a; circuit through the signaling device at the called station corresponding to the individual key depressed or actuated Likewise each or" the trunk answering keys T is provided with a third contact1'8, the purpose'of which will more clearly hereinafter appear, closed only when the trunk answering key is fully depressed to its way-down position. Each of the individual keys and the trunk and local answering keys T and L are of the locking type, so that when depressed it is locked in depressed position by a spring pressed latch plate 7. When locked in depressed position, the extreme right-hand or third contact 12 of the individual key is not closed, while the other" two are closed to] connect the telephone set with the conductors individual to the called station. When a trunk answering key T is locked in depressed position, the

which, when the bridge is closechfis energized to complete a locking circuit for relay 8. Relay 8 may be released by'the subsequent actuation of any trunk answering key T which, in closing its way-down right hand 8, causing the deenergization thereof.

Referring now to the operation of the system shown in the drawing, it will be assumed that the operator at the central office (not shown) the cord circuit thereat and the central office end of the trunk circuitand has projected ringingicurrent out over the trunk'circuit to cause the operationof a call bell 15, which of relay 1Q0 has made connection between a in the system illustrated in the drawing, is

shown associated ,with station A of the intercommunicating system. may thereforeserve as an answering station oft e. interceme nnieatins sy em far as This station A incoming calls over the trunk circuit are concerned. The attendant at station A, in response to the operation of the call bell 15, depresses the trunk answering key T. and 5'removes the receiver from the switchhook,

thereby connecting the telephone set of station A across the trunk circuit conductors 5 and 6 through contacts 16 and 17 of the trunkanswering key T and normal contact i 20 resistance 18, the winding-of relay 8, contact 19 of key H, conductor 20, and through.

ringing battery RB backto the other side of the talking battery TB. Relay S, on being energized, closes its alternate con tact and opens its normal contact, thereby disconnecting the telephone set from across the trunk circuit and connecting the bridge 9, 10, which includes the winding of relay 11, across the trunk circuit. The holding bridge is thereby substituted for the telephone set; Upon being connected across the "trunk circuit relay 11 is energized by current from the central oflice battery and upon being energized attracts its armature, closing its contact to establish a locking circuit for relay 8. Thislocking circuit may be traced 7 from one side oi. the talking battery TB through resistance 18, winding of relay 8, .contact of relay 11, conductor 21 through the battery RB to the other side of the talkring battery TB. As the individual key 2 is depressed, the plate 7 is actuated to release the trunk answering key T, opening contacts 16 and 1'? and preventing the coni nection of the telephone set of station A- With the trunk circuit when the telephone set of station B is subsequently connected therewith. vBy the closure of contacts 32 and 34 of key 2 upon the depression'thereof. the telephone set of station A is connected with the conductors 30 and 35 which are. in-. dividual to the station B. The depression of the individualkey 2 to its way-down position' causes the operation of the signaling device 25 at station B. The operating circuit forthis signaling device may be traced from one side of the ringing battery RB through conductors 26 and 27, switchhook contact28, contact and winding of signaling device 25, conductors 29 30 and 31, contacts 32 and 12 of the key 2, and conductors 33, 20 and 34, back to the other side of the ring- "ing battery RB. Key 2, after being depressed to its way-down position to cause the operation of the signaling device at sta- The momention'B, is then released and is locked in depressed position with its contacts 32 and-34 closed and contact 12 open. a V

' The party at station B, in response to the operation of the signaling device '25, de-

presses the local answering key L and re-' ant at station A may restore the receiver to so the switchhook. The party at B may then actuate (depress) the trunk answering key T, thereby releasing the local answering key L, which disconnects the telephone set of station'B from the conductors 30,35 and connects this telephone set with the trunk circuit through contacts 16 and 17 of the trunk answering key-T of station E. The trunk key in being depressed is fully depressed to its way-down position, to dc- 9c energize relay 8 by establishing a short cir-' cuit about this relay. This short circuit may be traced from the upper terminal of resistance 18 through conductors 42 and 43, contact 13 of the trunk answering. key T of station B, conductors 44, 45 and 34, to a terminal of the ringing battery RB. The relay 8 thereupon releases its armature, opening its alternate and closing its normal contact. The openingofits alternate contact opens the bridge and disconnects the winding of relay 11 from the trunk circuit. Belay 11 thereupon releases, opening its contact which is in the locking circuit 01 relay 8. The trunk answering key T of station B, after being depressed to its way-down p0sition, maythen be released, whereupon .itis locked in its depressed position, with its contacts 16 and 17 closed and its contact13 open. At the conclusion of the conversation the party at station Brestores the receiver to the switch-hook thereby permitting the release of the supervisory relay of the cord circuit at the central oflice whereupon a disconnect signal is given to the operator thereat.

I It is to be noted that this invention provides very simple means for holding the trunk circuit in substitution for the tele- W loo phone set of an intercommunicating sys- 12'0 tem, and in so doing utilizes a. very small amount of apparatus which 1S common to p the trunk circuit andpermits :the use of keys at the various stations of the intercr'" municating system which are of very simple construction. What is claimed is: I

' 1. In a telephone system in combination,

a plurality of subscribers stations, a trunk circuit multipled to the stations, a telephone set at each station adapted to be connected with the trunk circuit, a bridge including a relay for holding the trunk circuit in substitution of a telephone set, switching means including a, relay energized over a circuit independent of the telephonesets controlling such substitution, a locking circuit for the second relay established upon the energization of the bridged relay, a switching device for connecting a telephone set with the trunk circuit, and a disabling circuit for the second relay established upon the actuation of the switching device.

2. In a telephone system, in combination, a plurality of subscribers stations, a trunk circuit multipled to the stations, a telephone set at each station, a trunk key at each station having contacts controlling the connection of the telephone set thereat with the trunk circuit, one of the telephone sets being connected with the trunk circuit, a holding key'at each station, a bridge comprising a relay winding for maintaining the circuit continuity of the trunk circuit in substitution of a telephone set, a relay energized upon the actuation of a holding key over a circuit independent of the telephone sets to connect the bridge across the trunk circuit, and to disconnect the engaged telephone set from the trunk circuit, and a locking circuit for the second relay completed through a contact of the bridged relay upon the energization thereof.

3. In a telephone system, in combination, a plurality of subscribers stations, a trunk circuit multipled to the stations, a telephone set at each station, a trunk key at each station having contacts controlling the connecthe circuit continuity of 'the' circuit for the second relay established upon,

the subsequent actuationof a trunk key.

In witness whereof I'hereunto subscribe may name this 29th day of September, A. D. 1917. i

CHARLES W. KECKLER. 

